The invention relates to a direct drive for large-scale drives with a stator comprising segments and a rotor comprising segments.
Direct drives are coupled directly, i.e. without any transmission interconnected, to working machines. In particular in the case of large-scale machines, such motors are used as ring motors, for example in mills. Such ring motors are known from U.S. Pat. No. 1,224,933 and U.S. Pat. No. 3,272,444. Ring motors are multipole synchronous salient pole motors which are used for low-speed tube mills. In this case, the mill body is used as the hub of the rotor, i.e. the motor is arranged annularly around the mill body. The axial length of the laminate stack of the stator of the ring motor results, for example given predetermined capacity utilization, from the torque required for the mill.
In the case of ring motors with very large diameters, the stator, when viewed in the circumferential direction, is split into a plurality of segments in order to be able to provide the transport to the installation. The assembly of the stator required there in this case entails a plurality of problems since, in the case of conventional drum-coil windings, the winding of the stator cannot yet be completely inserted and checked in the factory. A certain number of drum coils extends over the respective separating joints of the mutually abutting segments and can therefore only be inserted after assembly on the installation.
In order to solve this problem, until now so-called split coils have been provided which have been inserted retrospectively on the installation into the slots of the stator. However, this represents considerable complexity in terms of work, and these split coils form the weakest link in the winding of the stator as a result of the insulation which is subsequently carried out and is required in the end winding region.